Interfacial electron-rich centers in MoOx/fine slag derived from mining waste enable durable Li-O2 batteries with enhanced kinetics

Abstract

Escalating coal gasification slag generation from the expanding coal chemical industry has intensified environmental and waste-management concerns. Converting coal gasification fine slag into functional energy materials offers a promising pathway for sustainable resource recovery from mining-related solid residues. Here, a heterostructured MoOx/fine slag electrocatalyst is prepared through a scalable pre-activation and hydrothermal growth route. Unlike most waste-derived or biomass-carbon cathodes that mainly serve as conductive hosts, this work leverages the slag-derived mineral–carbon matrix to construct a MoOx–slag heterointerface that drives charge redistribution and creates electronically activated interfacial sites referred to as interfacial electron-rich centers. These sites, associated with reduced Mo species, oxygen-vacancy-related defects, and oxygen-containing surface groups, accelerate oxygen redox kinetics and promote more reversible Li2O2 formation and decomposition. Under capacity-limited galvanostatic cycling, lithium–oxygen batteries using the MoOx/fine slag cathode deliver a low voltage polarization of 0.66 V at 500 mA g−1 and maintain stable operation for 246 cycles at a fixed capacity of 1000 mAh g−1. Compared with pristine MoO2, the polarization is reduced from 1.04 V to 0.66 V and the cycling duration is extended from about 200 h to over 1200 h, demonstrating markedly improved reversibility and durability. Ex situ characterization combined with density functional theory analysis indicates that the heterointerface modulates intermediate adsorption and steers Li2O2 reaction pathways. This study provides a waste-to-value strategy and mechanistic guidance for designing durable heterostructured cathode catalysts for advanced metal–air batteries.